1. Field of the Invention
The invention relates to a filter device for separating a mixture of solid substance and a liquid.
2. Description of Related Art
The manner in which a liquid filtration in which a liquid is separated from a solid substance by means of a filter can be best realized generally depends on the specific conditions. If it is wished to at least partially remove solid constituents from relatively large bulk quantities of liquid, it is usually advantageous to carry out (semi-)continuous liquid filtration by applying a filter device which is provided with a filter belt, wherein the filter belt forms an elongate (belt-like or strip-like) filter cloth for separating liquid and solid constituents. The advantage of applying such a filter device is that the filter belt is displaced through the filter device during the filtration process, whereby the part of the filter belt effectively used for filtering is in fact periodically changed, wherein the already used, contaminated part of the filter belt can be removed from the filter device. Transport of the filter cloth through the filter device generally takes place by pulling the cloth by making use of a conveyor belt, such as a chain or rubber belt, or by making use of a wheel, using which the filter cloth can be pushed forward. The known transport techniques all have drawbacks however. Pulling the cloth will result relatively quickly in tearing of the filter cloth, particularly in the case the filter cloth is not displaced homogeneously through the filter device, and this will generally result in leakage and thereby malfunction of the filter device. Pushing the filter cloth forward using a rotating wheel has the drawback that this method of displacement can result relatively quickly in slippage between the filter cloth and the rotating wheel, which will hamper and may even prevent displacement of the filter cloth. The forward pushing can moreover generally also result relatively easily in creasing of the filter cloth, this resulting in leakage and therefore malfunction of the filter device. The use of a separate conveyor belt such as a chain is in general structurally relatively complex and therefore generally entails relatively high production costs and operational costs. A drawback of the separate conveyor belt is moreover that a sealing of the filter cloth in the filter device can be relatively difficult to realize, which results in undesirable leakage in the filter device. A further drawback is that in the known filter device a plurality of electric motors, or at least a plurality of drives, are generally applied, which must be continuously mutually synchronized in order to prevent rucking or tearing of the filter cloth, which is found in practice to be exceptionally difficult.
An object of the invention is to provide an improved filter device for separating a mixture.